The invention relates to a storage battery system which can be used as a UPS.
Today, Uninterruptible Power Supplies (UPS) are being widely used in general offices to supply electric power to information devices such as servers until the information device normally terminates when power breaks down. Furthermore, it is under consideration to restrain use of commercial electric power by providing, in conjunction with a UPS, an independent power source using renewable energy such as solar-generated power or wind-generated power.
Japanese Patent Laid-Open No. 2003-348768 (Patent Document 1) discloses a UPS provided in conjunction with an independent power source. In the UPS described in the document, output from an independent power source and output of a secondary battery are converted into alternating current and output to an output terminal while a commercial AC power source breaks down. If the output power from the independent power source has surplus, regardless of either receiving commercial AC power or experiencing power outage, the surplus power is regenerated for the commercial AC power source.
Japanese Patent Laid-Open No. 2010-16989 (Patent Document 2) describes a power generating system which determines or predicts which of power selling or self-consumption is more advantageous when an independent power source is in conjunction with a commercial power system. Specifically, commercial power is supplied from the commercial power system to a domestic power line via a power meter for power selling/power purchase. Electric power generated by a renewable energy generation device is also supplied to the domestic power line. The power supplied to the power line is supplied to a domestic load and an information processing unit via a power distribution board. The information processing unit determines and predicts which of power selling and self-consumption is more advantageous.
Published Japanese Translation of PCT International Publication for Patent Applications No. 2010-512727 (Patent Document 3) discloses a power aggregation system for distributed electric resources (a smart grid). In one embodiment of the document, a service establishes individual Internet connections for a number of power resources such as electric vehicles which are intermittently connected to a power grid. The service then optimizes the power flow to meet the needs of each resource and each resource owner by aggregating the flow across a number of resources so that they are suited for the needs of the power grid.